Latinos make up the fastest growing ethnic subgroup in the U.S., yet our understanding about mechanisms of risk and protection has lagged far behind the growth rate. We do know that, for many Latino youngsters, risk for substance use/abuse grows substantially as they and their families move through the acculturation process. Moreover, data indicate that they are at greater risk for the co-morbid effects and consequences of substance use (e.g., school failure, incarceration, poor health). Theoretical models suggest that acculturation processes, along with other contextual factors (e.g., socioeconomic status, social support processes), exert their effects on youngster adjustment indirectly, by impacting more proximal variables (i.e., parenting practices). While numerous prevention efforts have targeted parenting practices in mostly non-minority families, few intervention models have been tested that address culturally specific risk and protective factors for Latino families. The proposed study will help fill this gap by conducting a randomized longitudinal efficacy trial of a culturally specific preventive intervention adapted from the Oregon Social Learning Center's Parent Management Training model. The program, developed over four years with the support of NIDA, will be evaluated in a sample of 240 Latino families with youngsters in the 6th through 8th grade. Fifty percent of the families will be assigned to the intervention condition, and 50% will be assigned to the control condition. The sample will also be blocked on the focal youngsters'nativity status (i.e., 50% U.S-bom and 50% foreign- bom). All families will be assessed using multiple methods and agents at five points over approximately a two-year period. The project aims are to: (1) examine the efficacy of a culturally specified parent training intervention for Latino families on decreasing family stress, improving effective parenting practices, and reducing youngster risk for substance use and related problems;(2) examine potential differential effects of the intervention as a function of youth nativity status, youth gender, and higher initial levels of youth problem behaviors;and (3) test the theory underlying the intervention by determining whether changes in youngster trajectories towards risk for substance use and related behavioral health problems are mediated by intervention related changes to targeted parenting practices.